The present invention relates to tools for cutting or coining metal.
Bolt cutters are used for severing metal bars, such as bolts or reinforcement bars, and are normally provided with long handles for leverage. The cutting may also take the form of creating perforations in metal profiles. Similar tools are also used for the coining (shaping) of metal profiles. A tool of that type typically comprises two jaws held together at their centers by parallel links. The rear ends of the jaws are spaced apart and connected by hinges to the front ends of the handles. The handles are pivotably connected with each other in such a way that when the cutter is maximally open, a relatively small handle motion is enough to get a certain jaw-closing motion, but when the edges of the jaws almost touch each other at the end of a cutting operation, a greater handle motion is needed for the corresponding jaw motion. In this way there is achieved a strongly variable leverage, with the greatest force at the end of the operation when the jaws have penetrated the work material maximally.
The edges of the jaws become worn, and are easily damaged if one tries to cut a hardened bar, and it is therefore a requirement that a user shall be able to take the jaws apart for regrinding after some damage occurs. The hinges must thus be disconnectable and have a defined position so that the lengths of both edges rest against each other at the end of the cut. It is thus known to give the jaws a synchronized angular motion by a tangential connection against each other between the parallel links to get a defined closed position, such as shown in U.S. Pat. Nos. 5,081,769 and 5,101,566 and 5,014,432.
During regrinding, one must normally grind more at the tips of the jaws to make the edges touch along the whole edge length in a jaw-closed position, whereby the rear ends of the jaws get a greater distance from each other. To make the closed position of the handles coincide with the closed position of the jaws, the distance between the hinges of the handles can be made adjustable, such as by changing the handle distance with a screw as shown in U.S. Pat. Nos. 5,081,769 and 5,101,566.
It is also known to simplify regrinding by making the distance between the joints of the parallel links adjustable by using eccentric bolts such as disclosed in U.S. Pat. No. 5,081,769. The present invention concerns a design of the tangential connection between the jaws, which gives less play and a better defined closed position for the jaws compared to previously known designs, and which simplifies adjustment of the edges to a parallel relationship after regrinding.